Mothers play a critical role in facilitating the development of biobehavioral regulation in the child. However, marital conflict is related to a host of negative parenting practices, and marital conflict's effect on parenting behavior is thought to be a key mechanism leading to child maladjustment. Despite strong evidence that conflict and hostility between marital partners spillsover to effect parenting behaviors, mechanisms explaining how affect and mood transfers between dyadic familial relationships remains poorly understood. However, theoretical and empirical frameworks suggest marital conflict to be a major stressor, and responsible for changes in stress responsive physiological systems. To date, no study has examined marital stress physiology as a mechanism by which marital conflict impedes the ability for a child to behaviorally and physiological regulate in the face of challenge. The proposed study aims to fill this knowledge gap by examining the extent to which marital conflict induced maternal stress physiology reduces a mother's ability to respond sensitively to her infant during distress. We will then address the implications for the infant, by examining the degree to which the infant physiologically reacts and recovers from distress with maternal support. Participants will include 150 married parents living with their biological child approximately 6 months of age. Using a randomized controlled design, we will assign couples to engage in either a conflict discussion (N= 75) or a non-conflict discussion (N=75) before engaging in a mother-infant freeplay. After the freeplay, the mother will be asked to soothe her distressed infant (the infant will undergo a standardized laboratory procedure designed to elicit distress). Four saliva samples will be collected from the mother surrounding the marital discussion and four samples will be collected from the infant surrounding the distress task. Samples will later be assayed for cortisol and salivary alpha amylase, markers of the two major components of the psychobiology of the stress response (the hypothalamic pituitary adrenal axis and the autonomic nervous system, respectively). We will first examine if marital conflict induced stress physiology is responsible for reduced sensitivity in maternal caretaking. We will then examine if maternal stress physiology is a mechanism by which maternal stress is transmitted to her infant by examining infant physiological reactivity and recovery to challenge with maternal support. PUBLIC HEALTH RELEVANCE: The proposed study aims to identify the physiological mechanisms by which marital conflict spills over into parenting behaviors and effects infant regulation. Specifically, we will be examining the effects of physiological reactivity surrounding marital conflict on maternal behavior and the infant's physiological reaction to, and ability to recover from distress with maternal support. The identification of physiological mechanisms is relevant because their discovery will provide a deeper understanding of the causes of maternal behavior and the implications for the development of child regulation, and provide the basis for new targets of family-based interventions.